In a switched beam system, the wireless communication beams are fixed. As such, wireless mobile devices must be handed off from one beam to the next as the mobile travels around a base station. Some wireless systems may employ hard handoff between beams (that is, the system does not provide any momentary overlapping coverage utilizing two or more beams). Hard handoffs are not desirable, however, as they may result in increased dropped calls and may reduce the overall system capacity relative to other handoff methods CDMA supports softer-handoffs between sectors, in which multiple sectors transmit to the mobile simultaneously, but softer-handoff relies on assistance from the mobile in the form of pilot signal strength measurements. Since the beams share a common pilot signal, pilot measurements from the mobile cannot distinguish between the beams, and thus the mobile cannot assist the base station in the selection of the transmit beams.
In at least some prior switched beam systems, there are typically multiple beams per sector, and one or more of these beams can be used to transmit to an intended wireless mobile device. The use of the multiple beams depends on both the wireless standard (e.g., CDMA, CDMA2000, and so forth) and the implementation of the standard. The optimal use of the beams depends on the pilot configuration; more specifically on whether or not (i) the standard and the mobile support the use of per-beam pilot signals; (ii) the standard and the mobile support the use of per-user pilot signals; or (iii) if only a common pilot signal can be used.
Softer handoffs between sectors of the same bases station is typically done in a mobile-assisted fashion using pilot strength measurements taken by the mobile and transmitted to the base station. For softer handoff:    1) typically all sectors transmit the traffic channel to a particular mobile with the same power allocation;    2) the mobile has knowledge if a sector is transmitting a signal intended for the mobile; and    3) the mobile combines the signal from a particular base station sector only if that sector is transmitting to the mobile.
For beam-to-beam handoff, the situation is usually somewhat different. Generally, with only a common pilot, the mobile does not know which beams within the sector are transmitting to the mobile and the mobile cannot separate and identify the signals from the different beams. Thus, the mobile combines the signal contributions from all beams that can be detected.
These handoff techniques appear to allow the transfer of a mobile from one beam to another. However, problems with previous systems limit the effectiveness of the transfers and inhibit some implementations. Further, previous systems can be expensive to implement because of the problems these systems must attempt to overcome. These systems often drop calls, have limited functionality, have reduced and/or limited system capacity and typically require additional circuitry. These limitations reduce the systems overall effectiveness and frustrate customers.
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